Finding Solutions for Tastier Tomatoes, Recycled Carbon Fiber, and Better Battery Performance

In this episode, explore three ways NREL researchers are seeking out energy solutions:  

• An experiment dubbed “No Photon Left Behind” examined if growing tomatoes under the filtered light spectrum of a semitransparent photovoltaic panels would make them grow faster, bigger, and tastier.  
• The BOTTLE consortium at NREL released a paper recently that looked at new methods for recycling carbon fiber composites, the high-strength, low weight materials made from epoxy-amine resins that encase long carbon fibers and form a stiff material found in many consumer products like bicycles, planes, and cars.  
• NREL researchers are using an advanced imaging tool called x-ray nanoscale computed tomography imaging – or nano-C-T imaging, to analyze batteries at the end of their useful life and reveal hidden flaws that give us insights into how battery materials change during its life. 

This episode was hosted by Kerrin Jeromin and Taylor Mankle, written and produced by Allison Montroy, Hannah Halusker, and Kaitlyn Stottler, and edited by Taylor Mankle, Joe DelNero, and Brittany Falch. Graphics are by Brittnee Gayet. Our title music is written and performed by Ted Vaca and episode music by Chuck Kurnik, Jim Riley, and Mark Sanseverino of Drift BC. Transforming Energy: The NREL Podcast is created by the U.S. Department of Energy’s National Renewable Energy Laboratory in Golden, Colorado. Email us at podcast@nrel.gov. Follow NREL on X, Instagram, LinkedIn, YouTube, Threads, and Facebook.

Transcript

[intro music, fades] 

Taylor: Welcome to The NREL Podcast, brought to you by the U.S. Department of Energy’s primary national laboratory for energy systems research, development, and integration. We’re highlighting the latest in advanced energy research and innovations happening at the lab. It’s Wednesday, July 9. I’m Taylor Mankle.

Kerrin: And I’m Kerrin Jeromin.  

Taylor: Kerrin we’ve got a fun episode today filled with some interesting stories, including a closer look at how some NRELians are working on new methods for how we can recycle carbon fiber composites. 

Kerrin: We’ll also learn about battery degradation and how NREL is working to improve domestic recycling processes.

Taylor: Let’s get started!

[music] 

Kerrin: Alright Taylor, now that the Fourth of July is behind us (I hope you had a great holiday, by the way) it feels really like summer is just here, right? Have you picked up any fun summer activities? 

Taylor: I’m actually really excited to be attempting (key word: attempt, there) to grow some tomatoes with my wife this summer, and they are growing faster than we can keep up with!

Kerrin: Yeah, I think we’re all attempting our gardens. Believe it or not tomatoes have actually been at the forefront of some pretty cool research happening at NREL lately. 

Taylor: That’s right! It’s a pretty cool, and pretty tasty project where NREL researchers spent last summer, well, gardening. 

Kerrin: They took a dozen tomato plants and housed them in two custom greenhouses on NREL’s campus. 

Taylor: While the summer did end in a taste test, these researchers weren’t just nurturing a hobby. They were trying to see if filtering certain spectrums of sunlight in the greenhouse would help the tomatoes grow more successfully. 

Kerrin: And now get this: Most plants use less than half the solar spectrum for photosynthesis—the rest is obsolete or even harmful to growth, and the plant has to spend extra energy to protect itself from those unneeded photons. 

Taylor: Through a process called “biomatching,” our researchers used semi-transparent photovoltaic material to filter sunlight into the exact light spectrum that tomatoes prefer. The researchers call this project “No Photon Left Behind.” 

Kerrin: I love that. And researchers determined through this project that filtering the light spectrum made the tomatoes grow faster and bigger—and more delicious, too. 

Taylor: NREL chemist Bryon Larson explained that when light comes into contact with a plant, there’s a lot of different things that can happen depending on the type and amount of light. 

Kerrin: So the key is figuring out what happens when we identify the plant light requirement—or that you know, goldilocks scenario—the just right spectrum and dose of light the plant actually needs to thrive. 

Taylor:  And—that leftover light that the tomatoes don’t need? It could be used to make electricity with the same transparent, organic photovoltaic modules that were used as filters for sunlight. 

Kerrin: Remember the name “No Photon Left Behind” — that should  make a lot more sense now. So the eventual goal is that these solar panels would both provide biomatched sunlight to plants and power the greenhouse they’re in. It’s a two-fer.

Taylor: You’ve got plant growth through photosynthesis and electricity generation through photovoltaics. Talk about multipurpose. Sign me up!

Kerrin: Right, OK, but the most important question here: How do the tomatoes taste? That’s the most important part, right?

Taylor: Right. It’s not everyday an experiment at NREL ends with a taste test—but this experiment did just that. They did a blind taste test comparing their biomatched tomatoes with store-bought tomatoes and the control group tomatoes grown under regular sunlight. 

Kerrin: The biomatched tomatoes and control group tomatoes seemed to tie for favorite, both beating out the store-bought ones. They tried the tomatoes by themselves, with some salt, some pepper, and even added some crackers—just to make sure they got the full taste test experience. 

Taylor: I’m getting hungry just thinking about it. I want to be invited to the next taste test.

Kerrin: I know right, I love snacks. So I will now go and eat some bruschetta all in the name of science. You should join me, Taylor.

[music] 

Taylor: Our next story is about a paper that came out recently from the BOTTLE consortium at NREL. Quick refresher: That stands for Bio-Optimized Technologies to keep Thermoplastics out of Landfills and the Environment. 

Kerrin: And just BOTTLE is a bit easier to remember, so we’ll go with that. So this research looked at new methods for how we can recycle carbon fiber composites—also known as C-F-Cs. 

Taylor: So CFCs are high-strength, low weight materials made from epoxy-amine resins that encase long carbon fibers. They form a stiff material found in many consumer products, like bicycles, planes, and cars. Using CFCs makes the products lighter and more efficient. 

Kerrin: It’s a high-value product because of its use, but there are some barriers to using CFCs because they’re so energy intensive to make, and there’s  really not a great way to economically recycle the materials currently. And that means they’re expensive, too. 

Taylor: NREL researchers found that deconstructing the epoxy resins found in CFCs with hot acetic acid could provide a scalable and affordable recycling solution. 

Kerrin: Acetic acid is  the main component found in vinegar—so it’s a pretty simple solution to get the job done. 

Taylor: And the researchers found that the result from the acetic acid didn’t impact the strength of the carbon fibers when recycled. 

Kerrin: To demonstrate this, they took 80 grams of a scrap mountain-bike frame made of composite materials and deconstructed it with the acetic acid. 

Taylor: Using the carbon fibers they had just extracted, they then made new composites that exhibited more than twice the strength-to-weight ratio of steel. 

Kerrin: Plus, the recycled carbon fiber is a LOT cheaper than conventional fiber. 

Taylor: And the process could be expanded to glass fiber composites like turbine blades, boat hulls, or car bumpers and hoods. 

Kerrin: Ultimately, instead of going to the landfill, waste becomes something highly valuable for high-performance, high-demand products.

Taylor: I think that’s a result we can all support. 

[music]

Kerrin: Our final story is about another component of a lot of consumer products: lithium-ion batteries. 

Taylor: It’s also kind of about recycling! 

Kerrin: Because the minerals that power these batteries—like lithium, nickel, cobalt, manganese, graphite—they’re highly valuable and also difficult to come by. 

Taylor: As battery storage capacity across the United States continues to grow, constraints on the mining, refining, and processing of these key minerals leaves our energy systems vulnerable to the fluctuations of foreign markets.

Kerrin: Right, currently, China has significant control of the battery supply chain, including 60% to 90% of global mineral processing for lithium, nickel, and cobalt.

Taylor: And while recycling batteries domestically seems like a good solution, traditional battery recycling methods don’t really offer an affordable, efficient way to do that. NREL researchers are studying an alternative method called direct recycling. 

Kerrin: But not all direct-recycled batteries are created equal. Microscopic damage within battery cells can build up over time, weakening performance in some batteries. 

Taylor: NREL researchers are using an advanced imaging tool called x-ray nanoscale computed tomography imaging—or, easier to say, nano-C-T imaging, to analyze batteries at the end of their useful life.

Kerrin: Nano-CT imaging can reveal those hidden flaws and give us insights into how battery materials change during its life. 

Taylor: Researchers found that while the end-of-life batteries showed similar energy capacities to brand-new battery cells, the charging rate had diminished significantly.

Kerrin: The main type of damage limiting battery performance was the cracking of particles embedded in the material microstructure. 

Taylor: As researchers continue to develop new direct recycling processes, they will need to address these severe cracks.

Kerrin: The findings are the first step to developing techniques to recover and refurbish high-quality materials that maximize battery performance. And NREL is up to that challenge. 

Taylor: Now that they’ve identified the extent of this cracking, they are evaluating new ways to process the end-of-life material to repair some of that damage. 

Kerrin: This means targeting mechanical changes to the material to avoid extensive chemical processing in favor of simplified and more efficient recycling methods.

Taylor: It makes these critical minerals we talked about more valuable and increases their lifespan and keeps them within the US supply chain.

Kerrin: A win, win, win situation.

[music] 

Taylor: I love all the cool solutions NREL researchers are coming up with lately— solutions that have real impact.

Kerrin: Yeah, especially when it comes to the tomato part, because I think that’s the best part, right? It's cool to see these tangible applications, not just with better tomatoes that are more delicious, but also better recycling solutions for materials in common consumer products, like the frame of the bikes we ride or the batteries in our car. 

Taylor: Absolutely. Now thanks for joining for another episode, everybody, of the NREL Podcast. Please make sure you leave us a review! We want to hear from you. 

Kerrin: We really do. And we’ll be back in two weeks with more news from NREL.

[music]

Kerrin: This episode was adapted from NREL news articles published in June 2025 by Wayne Hicks and Rebecca Martineau. Our theme music is written and performed by Ted Vaca and episode music by Chuck Kurnik, Jim Riley, and Mark Sanseverino, of Drift B-C. This podcast is produced by NREL’s Communications Office.